Microbe Motels: An Interactive Method to Introduce the Human Microbiome.

INTRODUCTION

The human body is occupied by an immense number of microorganisms collectively referred to as the “human microbiota” (10). Bacteria are the most abundant occupants of the microbiota, colonizing distinct body sites in a mostly innocuous manner (3, 4, 9). The most densely occupied region of the human body is the intestinal tract, and it comprises four main phyla, namely: Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria. Together, the intestinal microbiota plays a critical role in the development of the innate immune system (11) and in the provision of continued protection against infection (8). Poor diet, lifestyle, and genetic factors alongside antibiotic treatment can cause dysbiosis, or imbalance, of the gut microbiota (2) (see Appendices 1 and 2). If dysbiosis remains after perturbation—i.e., after the system has been disturbed due to infection or serious illness—, the host may become prone to chronic inflammation or to the development of chronic illnesses such as ulcerative colitis and Crohn’s disease (5).

The microbiome is a heavily studied part of the human body, and the resulting research is regularly covered by popular media sources. Interest is particularly high given the increasing number of links between dysbiosis of the intestinal microbiota and obesity, depression, and rheumatoid arthritis (1, 6, 7). However, it is a challenging topic to discuss with people who have little to no knowledge of microbiology. Microbe Motels is a simple, fun, interactive activity that allows the balance of the intestinal microbiota to be explored. The format facilitates engagement as participants are encouraged to think about the roles of distinct bacterial phyla through hands-on activities. Microbe Motels can be easily recreated in a classroom environment and emphasizes the positive roles microbes play in the human body.

PROCEDURE

Safety considerations: Safety glasses and lab coats are recommended when using pipettes. Ensure participants do not have a wheat/flour allergy or intolerance in the event of accidental ingestion.

The materials specified provide for five learners sharing roles during the activity (see Appendix 3):

Printout of “Bob” and small stickers (Appendix 4)

Red, yellow, and blue poster paint in matching colored pots with plastic pipettes (or spoons)

Full bottle of drinking water

Icing piping bag and scissors

Crushed Wheat Biscuit Cereal in storage container

Flour in green pot with tablespoon

Toy toilet, or small container, and plain paper cupcake case

Wipeable tablecloth and wet wipes

Refuse bag for disposal

Preparation and set-up

Communicators should be fully versed with the supplementary background information and able to recall relevant information (Appendices 1 and 2). First, set up a table at a height suitable for younger children ensuring sufficient space for five learners. Label colored tubs with a bacterial phylum: Bacteroidetes (blue), Firmicutes (red), Actinobacteria (yellow), and Proteobacteria (green) (Fig. 1). Add flour to the green tub and the paint (diluted 1:1 with water) to the other tubs. Line a miniature toy toilet (or other suitable container) with a cupcake case. All other materials (e.g., water bottle, scissors, and crushed wheat biscuits) should be kept near the communicator.

FIGURE 1

Activity set-up using splash-proof mat, color coordinated tubs, and clear labeling of bacterial phyla.

Activity

Welcome learners and gauge their background knowledge by asking what they know about bacteria. Use this information to lead a brief discussion introducing bacteria with the goal of eliminating the misconception that “all bacteria are bad.” Highlight that bacteria live all around us, including on and in our bodies. Introduce the learners to “Bob” (Appendix 4) and ask them to place a sticker to indicate where bacteria might live. Every exposed surface of the body is colonized to varying degrees, ergo, no learners can be wrong! Next, explain that the intestinal tract is the most heavily occupied region of the body and that there are many different types of bacteria that live within it. Highlight that the resident microbes complete important “tasks” that help us and in return we provide nutrients: we are in effect “Microbe Motels.”

Introduce “Bob’s tummy” (the piping bag). Guide learners through each “tub of bacteria” highlighting the name of the phylum and the role the bacteria play as part of the intestinal microbiota (Appendices 1 and 2). The proportion of the bacterial phyla present in the intestine can be discussed at different levels of detail depending on the level/age/interest of the audience. Learners begin by adding “Proteobacteria” (flour) to the bag with a spoon and then, using pipettes, participants add volumes of liquid “bacteria” (colored water) to Bob’s tummy in proportions deemed to be correct based on the information provided. Ask the learners what else we eat (food and water) to break up the activity and re-engage. First add “food” (crumbled biscuit cereal) to the bag to allow the communicator to gauge how much water is needed. Learners should be encouraged to add a small amount of water. Then “digest” the contents by repeatedly squeezing the bag, but ensure that the top of the bag is held tightly closed! Cut off the sealed end of the piping bag and allow participants to squeeze the contents into the miniature “toilet.” Discuss the “product” noting if it looks of solid consistency and brown in color (i.e., “healthy”) and identify adjustments that could be made to improve it. This can then be related back to the key learning objective that the correct balance of intestinal bacteria is required for our health.

CONCLUSION

This novel activity conveys the concept and importance of the human microbiome. The hands-on “yuck” factor has significant appeal and facilitates open discussions. The simplicity of the activity allows delivery in diverse environments, from large science engagement events to small classroom activities. The additional resources will support educators and further enhance the learning experience for participants. To date, this activity has been presented at public science events and overall feedback suggests that this excellent activity is an engaging way of conveying an important, current scientific topic to a broad audience.

Appendix 1: Glossary

Appendix 2: Background information for communicator

Appendix 3: Instructions for activity preparation

Appendix 4: Image of “Bob” for printing